I can't select faces with left mouse button
This is characteristic to blender. With the left mouse button you change the position for the 3d cursor and with the right mouse button you can select objects.

In edit mode you can use the W shortcut, which give you a list of modelling actions. You can also use the left bar or the options in the menubar below.




Take a look at this tutorial about navigating in Blender:
http://www.katsbits.com/tutorials/blender/learning-keyboard-mouse-navigation.php